We have developed a technology with which we can study the proteins in nerve terminals of certain neurons in the visual system. Using axonal transport of labeled protein from cell bodies to distant nerve terminals, we can isolate a region of the brain in which the only labeled proteins will be in nerve endings. The labeled proteins can be separated from each other completely using the two-dimensional gel electrophoresis system. In preliminary experiments, 35S-methionine has been injected into the vitreous of Dutch-belted rabbits, and proteins transported to nerve terminals in the lateral geniculate nucleus and in the superior colliculus have been compared. In both nuclei over 100 proteins can be identified. Although the majority of the labeled proteins are identical in both nuclei, about 12 proteins are reproducibly different, suggesting that the technique provides a "fingerprint" of a given tract. We have also taken advantage of the detailed studies on the effects of visual deprivation of the rabbit to study changes in protein composition in nerve terminals. At least one protein is unequivocally lost from the nerve terminals of both the lateral geniculate nucleus and the superior colliculus after visual deprivation of immature rabbits and one extra protein is made. We propose to confirm these observations, perform some essential control experiments and to extend the technology in new directions. In particular, we need to know whether visual deprivation affects mature rabbits and whether the differences between colliculus and geniculate corresponds to slightly different transport rates. We intend to extent the technology to study fast and slowly transported proteins, changes during normal visual development, and after cortical ablation. We also will compare proteins sent to a single target nucleus from two cell body locations, the retina and the visual cortex. Finally we will attempt to subcellular localizations of proteins of interest. Our long term goal is to establish a way of studying identifiable protein changes during the normal and abnormal development of the visual system, as a molecular approach to brain plasticity.